Medical drainage catheters placed over guide wires have been used for over 40 years to drain fluid or air from various body cavities. Some applications for over-the-wire medical drainage catheters include placement within the thorax for drainage of gas to treat pneumothorax, placement within the thorax to drain fluid, placement within abscesses to drain purulent fluid, placement within the urinary tract to drain urine or purulent fluid in cases of urinary tract obstruction, and placement within the biliary tree to drain bile or purulent fluid in cases of biliary obstruction.
Although medical tube drainage is effective at curing some of these conditions, very often chronic tube drainage is required either indefinitely or permanently. In order to optimize normal function of tube drainage catheters, they are usually put on a maintenance schedule where they are changed at routine intervals. The most frequent way that tube drainage catheters are changed is by placing a guidewire through their lumens and out their distal tips, then removing the old catheter, then introducing the new catheter into the body over the guidewire, then removing the guidewire. However, a considerable limitation of chronic tube drainage is blockage of the distal end due to inspissation or precipitation of proteinaceous or mineral debris, which happens frequently when tubes are left in place chronically. When this happens, it may be impossible to pass the guide wire through the lumen of the drainage catheter and out of its tip. In some cases, there may be compaction of the retention suture down the lumen of the drainage tube as the guidewire is advanced, further narrowing the opening at the catheter tip and impeding passage of the guide wire out of the catheter tip. The present invention offers a solution that enables routine drainage tube exchange over a guide wire by allowing easier passage of the guidewire through the tip of the drainage catheter.
In one embodiment of such a modified tube drainage catheter, the tip of the catheter has a variable configuration, such that it is tapered and cone-shaped as it is introduced into the body, but under pressure of guide wire passage can, if resistance is met, alter its configuration to that its distal opening is wider than its original configuration. One way to achieve a distal tip with a variable lumen diameter would be to fashion longitudinal slits through the wall of the drainage catheter at the distal tip, which could then widen as a guide wire was passed when it meets resistance. Another possible way to achieve a tip with a variable opening would be to place numerous perforations through the material at the tip, rendering it mechanically weak and allowing a guide wire to perforate the material at the tip without passing out of the endhole. Another embodiment of a variable opening at the tip would be to have very thin catheter material at the tip, such that advancement of the guide wire against resistance at the tip would rupture the material when guide wire resistance is met, allowing the guide wire to exit the catheter at or near the tip end.
Another feature of an embodiment of the invention is that any suture wires or retention mechanism are outside of the lumen of the drainage catheter as the catheter exits the body space to be drained, and remain external to the catheter lumen as the catheter exits the body. Using such an embodiment of a drainage catheter retention system, the retaning sutures can be removed entirely from the device prior to placement of the guidewire, eliminating the possibility of the retaining sutures from being compacted within the catheter lumen by advancement of a guide wire through the lumen.
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